In document R1-082254, “TS36.213 CR 19 Rev1 v8.2.0”, May 2008, a number of features were agreed upon regarding the transmission mode and DCI (downlink control information) for the 3GPP LTE system. Among other things, it was agreed that a mobile device shall receive Physical Downlink Shared Channel (PDSCH) broadcast control transmissions, namely paging, Random Access CHannel (RACH) Response, and Broadcast Control CHannel (BCCH) associated with DCI formats 1A or 1C signaled by a Physical Downlink Control Channel (PDCCH) in the common search spaces. Additionally, the mobile device is semi-statically configured via higher layer signaling to receive PDSCH data transmissions signaled via PDCCH mobile device specific search spaces based on one of the following transmission modes: 1) single-antenna port (port 0); 2) transmit diversity; 3) open-loop spatial-multiplexing; 4) closed-loop spatial multiplexing; 5) multi-user MIMO; 6) closed-loop rank=1 preceding; 7) single-antenna port (port 5).
A mobile device or user equipment (UE) not configured to receive PDSCH data transmissions based on one of the transmission modes may receive PDSCH data transmissions with DCI format 1A signaled by a PDCCH in its mobile station specific search spaces or the common search spaces.
A mobile device semi-statically configured with a transmission mode shall receive PDSCH data transmissions associated with a reference DCI format signaled by a PDCCH in its mobile device specific search spaces based on Table 1. In the case of transmission modes 1, 2, and 7, a UE shall receive PDSCH data transmissions associated with reference DCI formats 1 or 1A in its UE specific search spaces or DCI format 1A in the common search spaces. A UE with reference DCI format 1B or 2 also may also receive PDSCH data transmissions associated with DCI format 1A signaled by a PDCCH in its UE specific search spaces or the common search spaces. A UE shall be configured to use the PUCCH or PUSCH feedback mode corresponding to its reference DCI format.
A table of the transmission mode that is supported by reference DCI formats is shown in Table 1 below:
TABLE 1Reference DCI Format supportedby transmission modeTransmissionReference DCIModeFormat11, 1A21, 1A32425TBD61B71, 1A
Therefore, there is a need in the art for an improved data format switching between DCI formats.